Create process_manager app

[AdrianDAlessandro]

Description

This PR creates a new app called process_manager and shifts all the behaviour for the process manager from the main app to the new app. The only details remaining in the main app are:

• The user model (plus associated admin, migrations, and login template)
• The base and navbar templates
• The Kafka consumer management command

Some more details:

• The main app index page still requires a login, all it shows is two buttons to navigate to the other apps from.
• The process_manager views and urls are namespaces under the path prefix /process_manager/
• The tests have been split into sub-folders for each app
• The navbar template is newly separated out and has additional nav links to the two apps, which can only be viewed when authenticated

Caveat:

• It's possible some of the behaviours currently in the process_manager will end up being common to the controller, but this information is not yet known for sure. If that occurs in the future, we can simply shift things back to the main app ass needed.

This PR builds on #132 and should be merged after that.
Close #113

Type of change

• Documentation (non-breaking change that adds or improves the documentation)
• New feature (non-breaking change which adds functionality)
• Optimization (non-breaking, back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)
• Breaking change (whatever its nature)

Key checklist

• All tests pass (eg. python -m pytest)
• The documentation builds and looks OK (eg. python -m sphinx -b html docs docs/build)
• Pre-commit hooks run successfully (eg. pre-commit run --all-files)

Further checks

• Code is commented, particularly in hard-to-understand areas
• Tests added or an issue has been opened to tackle that in the future. (Indicate issue here: # (issue))

[AdrianDAlessandro]

@cc-a Can you make sure I have merged this with #130 properly?

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (4a26086) to head (b78d0f6).

Additional details and impacted files

@@               Coverage Diff                @@
##           controller-app      #133   +/-   ##
================================================
  Coverage          100.00%   100.00%           
================================================
  Files                   5         5           
  Lines                  44        44           
================================================
  Hits                   44        44           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[cc-a]

LGTM. htmx stuff still seems to be working.